Search Results (1,913)

This study aims to assess, through individual performance, the influence of supply chain managerial competency of logistics managers on company logistics performance, taking into account the moderating effects of education and work experience. Using an empirical survey of Vietnamese developing nation logistics companies, this study applied the PLS-SEM approach for data analysis including assessments of mediation and moderation. The sample comprised 272 valid replies from a structured survey aimed at managerial personnel. The findings demonstrate that the competencies of logistics managers substantially improve individual performance, hence mediating the favorable correlation between management competencies and organizational logistics performance. The results indicate that both education and experience enhance these linkages at both individual and organizational levels. This study advances the application of RBV theory by highlighting human capital as an essential, distinctive resource that, when augmented by education and experience, enhances organizational performance. Nevertheless, this study’s shortcomings encompass a concentration on the Vietnamese logistics sector, indicating the need for future research across various businesses and geographical settings. These observations highlight the necessity for specialized education and training programs to develop managerial competencies for enduring organizational effectiveness. Full article

Objective: This study aims to evaluate long-term physical and motor performance in children aged 3–6 years following congenital diaphragmatic hernia (CDH) surgery, in comparison with healthy peers. While existing research emphasizes prognostic factors such as the lung to heart ratio (LHR) and liver position, few studies address physical outcomes in early childhood post-surgery. Methods: A total of 31 children who underwent neonatal CDH surgery (study group) and 41 age-matched healthy children (reference group) were assessed. The Wrocław Test and the Ozierecki Metric Scale (modified by Barański) were used to evaluate strength, endurance, motor coordination, and agility. Results: Findings indicated that children in the CDH group had significantly lower scores in physical performance, particularly in endurance and motor coordination, compared to their healthy peers. Strength differences were present but less pronounced. Conclusions: Children post-CDH surgery exhibit slightly delayed physical and motor development, suggesting a potential need for targeted physical activity programs in early childhood to support improved outcomes. Full article

This paper proposes a deep learning-based anomaly detection method using time-series vibration and current data, which were obtained from endurance tests on driving modules applied in industrial robots and machine systems. Unlike traditional classification models that depend on labeled fault data for detection, acquiring sufficient fault data in real industrial environments is highly challenging due to various conditions and constraints. To address this issue, we employ a semi-supervised learning approach that relies solely on normal data to effectively detect abnormal patterns, overcoming the limitations of conventional methods. The performance of semi-supervised models was first validated using a statistical feature-based anomaly detection approach, from which the GCN-VAE model was adopted. By combining the spatial feature extraction capability of Graph Convolutional Networks (GCNs) with the latent temporal feature modeling of Variational Autoencoders (VAEs), our method can effectively detect abnormal signs in the data, particularly in the lead-up to system failures. The experimental results confirmed that the proposed GCN-VAE model outperformed existing hybrid deep learning models in terms of anomaly detection performance in the pre-failure section. Full article

Deploying sensors to target locations using UAV platforms can effectively address the issue of limited aerial endurance in micro-UAVs. This paper introduces a launch method based on the crossbow principle, which is capable of concealing the deployment of heavy sensors. Given that the size and mass of the launcher on the UAV should be minimized, optimizing the structural energy storage performance of the launcher is essential. Initially, a static energy storage model for the launcher was developed, and criteria for evaluating the energy storage coefficient were established. Using the control variable method, the impact of seven structural parameters on the energy storage performance was analyzed. Based on these findings, a particle swarm optimization algorithm was proposed to optimize six parameters, aiming to maximize the energy storage coefficient. Subsequently, the bending stiffness coefficient of the launcher’s bow limb can be adjusted according to the specific application scenario to manage the energy storage within a reasonable range. Calculations revealed that after optimization, the maximum draw force was only 0.675 times that of the original plan under the same energy storage conditions. With the same maximum draw force, the energy storage capacity was 1.5 times higher than the original plan, indicating a significant optimization effect. This optimization approach provides a theoretical foundation for the energy storage optimization analysis of UAV-launched crossbow-based systems. Full article

Background/Objectives: Core strength diagnostics often focus on measuring core endurance rather than maximal core strength or core power. This study investigates whether core strength can be considered as a general ability that can be measured by a single core strength test or whether it needs to be differentiated into several components. Methods: Forty-two adult sports students (n_female = 20; n_male = 22; age: 24.0 ± 2.9 years; body height: 179.0 ± 9.8 cm; body mass: 75.2 ± 12.7 kg; body fat: 18.0 ± 6.8%) participated in two randomized testing sessions in a laboratory setting. Standard measurements, such as peak rate of force development (pRFD), maximal voluntary contraction (MVC), and holding time, were taken isometrically during four exercises (ventral, dorsal, and lateral right and left). Results: A principal component analysis (PCA) extracted three principal components from twelve different core strength variables. The three identified components explained 73.3% of the total variance and were labeled as (a) maximal core strength, (b) core endurance, and (c) core power. Conclusions: The results suggest three principal components of the core strength construct, as well as their differentiation, may be imperative. These findings should be taken into account in sport science and sports practice as they may be helpful in planning sport-specific diagnostic, performance-oriented training, and injury prevention programs. Full article

Background: This study examines genetic variations in the systemic oxygen transport cascade during exhaustive exercise in physically trained tactical athletes. Research goal: To update the information on the distribution of influence of eleven polymorphisms in ten genes, namely ACE (rs1799752), AGT (rs699), MCT1 (rs1049434), HIF1A (rs11549465), COMT (rs4680), CKM (rs8111989), TNC (rs2104772), PTK2 (rs7460 and rs7843014), ACTN3 (rs1815739), and MSTN (rs1805086)—on the connected steps of oxygen transport during aerobic muscle work. Methods: 251 young, healthy tactical athletes (including 12 females) with a systematic physical training history underwent exercise tests, including standardized endurance running with a 12.6 kg vest. Key endurance performance metrics were assessed using ergospirometry, blood sampling, and near-infrared spectroscopy of knee and ankle extensor muscles. The influence of gene polymorphisms on the above performance metrics was analyzed using Bayesian analysis of variance. Results: Subjects exhibited good aerobic fitness (maximal oxygen uptake (VO₂max): 4.3 ± 0.6 L min⁻¹, peak aerobic power: 3.6 W ± 0.7 W kg⁻¹). Energy supply-related gene polymorphisms rs1799752, rs4680, rs1049434, rs7843014, rs11549465, and rs8111989 did not follow the Hardy–Weinberg equilibrium. Polymorphisms in genes that regulate metabolic and contractile features were strongly associated with variability in oxygen transport and metabolism, such as body mass-related VO₂ (rs7843014, rs2104772), cardiac output (rs7460), total muscle hemoglobin content (rs7460, rs4680), oxygen saturation in exercised muscle (rs1049434), and respiration exchange ratio (rs7843014, rs11549465) at first or secondary ventilatory thresholds or VO₂max. Moderate influences were found for mass-related power output. Conclusions: The posterior distribution of effects from genetic modulators of aerobic metabolism and muscle contractility mostly confirmed prior opinions in the direction of association. The observed genetic effects of rs4680 and rs1049434 indicate a crucial role of dopamine- and lactate-modulated muscle perfusion and oxygen metabolism during running, suggesting self-selection in Swiss tactical athletes. Full article

High-intensity training (HIT) has commonly been the most effective training method for improvement in maximal oxygen uptake (VO_2max) and work economy, alongside a substantial volume of low-intensity training (LIT). The polarized training model combines both low- and high-intensity training into a specific training intensity distribution and has gained attention as a comprehensive approach. The objective of this review was to systematically search the literature in order to identify the effects of polarized training intensity distribution on VO_2max, peak oxygen uptake (VO_2peak), and work economy among endurance athletes. A literature search was performed using PubMed and SPORTDiscus. A total of 1836 articles were identified, and, after the selection process, 14 relevant studies were included in this review. The findings indicate that a polarized training approach seems to be effective for enhancing VO_2max, VO_2peak, and work economy over a short-term period for endurance athletes. Specifically, a training intensity distribution involving a moderate to high volume of HIT (15–20%) combined with a substantial volume of LIT (75–80%) appears to be the most beneficial for these improvements. It was concluded that polarized training is a beneficial approach for enhancing VO_2max, VO_2peak, and work economy in endurance athletes. However, the limited number of studies restricts the generalizability of these findings. Full article

Background and Objectives: Sport climbing’s popularity has grown with its inclusion in the Olympics and increased accessibility. Understanding the relationship between hand dominance, grip strength, endurance, and the involvement of masticatory and neck muscles can provide valuable insights into the neuromuscular adaptations specific to sport climbing, potentially aiding performance optimization and injury prevention in intermediate and advanced climbers. This study analyzes if the dominant hand has greater isometric endurance and isometric manual grip strength parameters than the non-dominant one and examines its relation to the masticatory and neck muscles in intermediate and advanced sport climbers. Materials and Methods: The study was conducted on 41 participants who were divided into two groups according to the IRCRA classification. A level 2 (Lv2) group consisting of 18 climbers and a level 3 (Lv3) group consisting of 23 climbers were identified. First, isometric manual grip strength and isometric endurance were measured using a dynamometer following the protocol of the first three and the last three repetitions (PC3) and the first six and the last six repetitions (PC6). Next, masticatory and neck muscle activity was assessed using surface electromyography, following the same protocol. Results: Greater activity of the temporalis muscle was observed on the non-dominant side in the advanced climber’s group (p = 0.045). The decrease in bioelectric activity was lower on the dominant side in group Lv3 compared to Lv2. In intermediate climbers, the bioelectrical activity of the masseter muscles in PC3 was greater on the non-dominant side, and in PC6, was greater on the dominant side. The digastric muscles showed a greater decrease in isometric endurance on the non-dominant side. Conclusions: Advanced climbers demonstrated greater isometric endurance and isometric manual grip strength parameters in both dominant and non-dominant hands compared to intermediate climbers. The masticatory muscles exhibited higher electromyographic activity on the non-dominant side in the masseter muscles and higher electromyographic activity on the dominant side in the temporalis muscles and digastric muscles. Full article

(1) Background: Most rare disease patients endure long delays in obtaining a correct diagnosis, the so-called “diagnostic odyssey”, due to a combination of the rarity of their disorder and the lack of awareness of rare diseases among both primary care professionals and specialists. Next-generation sequencing (NGS) techniques that target genes underlying diverse phenotypic traits or groups of diseases are helping reduce these delays; (2) Methods: We used a combination of biochemical (thin-layer chromatography and high-performance liquid chromatography-tandem mass spectrometry), NGS (resequencing gene panels) and splicing assays to achieve a complete diagnosis of three patients with suspected metachromatic leukodystrophy, a neurologic lysosomal disorder; (3) Results: Affected individuals in each family were homozygotes for harmful variants in the ARSA gene, one of them novel (c.854+1dup, in family 1) and the other already described (c.640G>A, p.(Ala214Thr), in family 2). In addition, both affected individuals in family 2 were carriers of a known pathogenic variant in an additionallysosomal disease gene, GNPTAB (for mucolipidosis III). This additional variant may modify the clinical presentation by increasing lysosomal dysfunction. (4) Conclusions: We demonstrated the deleterious effect of the novel variant c.854+1dup on the splicing of ARSA transcripts. We also confirmed the involvement of variant c.640G>A in metachromatic leukodystrophy. Our results show the power of diagnostic approaches that combine deep phenotyping, NGS, and biochemical and functional techniques. Full article

People affected by mitochondrial myopathies (MITOs) are thought to have impaired skeletal muscle oxygenation. The aims of this study were to measure skeletal muscle mitochondrial capacity in MITO participants and able-bodied (AB) participants and evaluate the influence of muscle-specific endurance training in one MITO participant. Participants (n = 7) with mitochondrial disease and controls (n = 9) were tested (ages 18–54 years). Mitochondrial capacity (mVO₂max) was measured using the rate constant of recovery of oxygen consumption (mVO₂) after exercise in the forearm flexor muscles with near-infrared spectroscopy (NIRS). One MITO participant was tested before and after performing 18 forearm exercise sessions in 30 days. There were no differences between MITO and AB participants in mVO₂max (MITO: 1.4 ± 0.1 min⁻¹; AB: 1.5 ± 0.3 min⁻¹; p = 0.29), resting mVO₂ (MITO: −0.4 ± 0.2%/min; AB: −0.3 ± 0.1%/min; p = 0.23), or initial post exercise oxygen consumption rates (MITO: 4.3 ± 1.2%/min; AB: 4.4 ± 1.4%/min; p = 0.9). Exercise oxygen desaturation was greater in MITO (39.8 ± 9.7% range) than in AB (28 ± 8.8% range) participants, p = 0.02. The MITO participant who trained increased her mitochondrial capacity (58%) and muscle-specific endurance (24%) and had reduced symptoms of muscle fatigue. We found no evidence supporting in vivo impairment of forearm muscle mVO₂max in genetically confirmed MITO participants. This is consistent with studies that report increased mitochondrial content, which offsets the decrease in mitochondrial function. Positive muscle adaptations to endurance training appear to be possible in people with MITOs. Characterization of study populations will be important when interpreting the relationship between in vivo mitochondrial capacity and mitochondrial disease. Full article

This study examines the influence of muscle strength on performance metrics in volleyball, addressing the need to understand how specific and non-specific strength training impacts athletic capabilities. A cohort of athletes underwent various strength tests, including squats (SQs), bench presses (BPs), and deadlifts (DLs), to assess their force and power during various forms of test. Lactate thresholds (LT₁ and LT₂) were also measured to evaluate aerobic and anaerobic capacities. The median speed at LT₁ was 1.80 m/s, and LT₂ was determined at a mean velocity of 2.56 m/s. Notably, a correlation was found between SQ performance and total points scored (p = 0.040, r = 0.285), while upper body strength was strongly correlated with performance metrics, showing significant relationships with points scored (p = 0.0001, r = 0.690) and peak power during BPs (p = 0.0001, r = 0.587). The findings suggest that targeted strength training enhances physical capabilities and improves technical and tactical performance in volleyball, highlighting the critical role of muscle strength in athlete selection and training strategies. Full article

This study investigates the impact of rotor spacing on the aerodynamic performance of a coaxialcopter and promotes an innovative regulated control strategy for the coaxial drone. The present research introduces a coaxialcopter with variable rotor spacing, and employing finite element numerical simulations, we assess the aerodynamic behavior of this novel configuration. Through comprehensive measurements and analysis of its aerodynamic performance across varying rotor spacings from 0.1 R to 1 R, we validate the effectiveness of a rotor-spacing control strategy for enhancing takeoff maneuvers. The numerical simulation and experiment results reveal that the performance characteristics of both the upper and lower rotors converge toward that of a single rotor as the space ratio increases, along with a reduction in their thrust fluctuations and aerodynamic performance periodicity. Considering stable power consumption patterns and endurance performance, we analyzed the interrelations binding the pitch distance of the rotors, rotational speed, and pitch angle, vis à vis the thrust coefficient and power coefficient. Through the parameter optimization method, we demonstrate that adjusting rotor spacing offers a practical means to enhance payload capacity without increasing the power input, thereby improving efficiency, which validates the practicality and efficacy of the parameter optimization approach. Furthermore, optimizing rotor spacing for specific operational scenarios enhances overall aerodynamic performance, suggesting a viable flight control strategy for takeoff and landing conditions for coaxial drones. Full article

Unlike traditional building structures, transmission tower foundations endure significant vertical and horizontal loads, with particularly high uplift resistance requirements in complex terrains. Moreover, challenges such as difficult material transport and low construction efficiency arise in these regions. This study, based on practical projects, proposes a novel high uplift resistance prestressed concrete prefabricated foundation (HURPCPF) tailored for transmission line systems in complex terrains. A refined finite element model is developed using ABAQUS to analyze its performance under uplift, compressive, and horizontal loads. Comparative studies with cast-in-situ concrete foundations evaluate the HURPCPF’s bearing capacity, while parametric analysis explores the impacts of foundation depth and dimensions. The results show that the proposed HURPCPF exhibits a linear load–displacement relationship, with uniform deformation and good integrity under compressive and uplift conditions. During overturning, the tilt angle is less than 1/500, meeting safety standards. The design of prestressed steel strands and internal reinforcement effectively distributes tensile stress, with a maximum stress of 290 MPa, well below the yield stress of 400 MPa. Compared to cast-in-situ concrete foundations, the displacement at the top of the HURPCPF’s column differs by less than 7%, indicating comparable bearing performance. As foundation depth and size increase, vertical displacement of the HURPCPF decreases, enhancing its uplift resistance. Full article

Mental fatigue is an important factor affecting athletes’ performance. Explaining the effects of mental fatigue on sports performance from a theoretical point of view can help us deeply understand the interconnection between mental fatigue and sports performance and conduct effective interventions based on this. Combining the relevant literature in China and abroad reveals that the current academic theories on the mechanism of sports fatigue include motivational control theory, underload theory, neural waste disposal hypothesis, and resource depletion theory. The effects of mental fatigue on performance are reflected in aerobic endurance, sports decision-making, tactical performance, and technical performance. Current coping strategies for mental fatigue include physiological coping strategies based on nutrition (caffeine), odor, and noninvasive neuromodulation techniques and psychological and behavioral coping strategies based on music and positive thinking. Full article

Background: Ketone body supplementation has emerged as a potential ergogenic aid in cycling. Exogenous ketones, primarily in the form of beta-hydroxybutyrate, offer an alternative fuel source, bypassing the need for strict ketogenic diets. However, the science surrounding their efficacy remains complex, with mixed field findings and unexplored mechanisms. Methods: A narrative review of the current literature was conducted, synthesizing studies on the metabolic and cognitive effects of ketone bodies in cycling. The review included an examination of human and mechanistic studies, along with emerging hypotheses on ketone bodies and their role in modulating red blood cell production and recovery processes. Results: Ketone body supplementation can theoretically spare glycogen, reduce muscle protein breakdown, enhance fat oxidation, and improve recovery by mitigating oxidative stress and inflammation. Additionally, ketone bodies may support cognitive function, reducing perceived mental fatigue. Preliminary evidence also suggests a potential role in modulating erythropoietin levels through histone acetylation, though further research is needed to establish its impact on oxygen delivery. Despite the theoretical potential, the practical assessment of field studies shows disappointing effects on performance from ketone body supplementation. Conclusions: While ketone bodies offer several potential benefits for cyclists, the variability in individual responses, lack of long-term data, and inconsistent findings in performance studies highlight the need for further research. Optimizing dosage, timing, and understanding the broader implications of ketone body supplementation will be crucial for their practical application in cycling. Full article